CODE  CODE1  CODE2
101    201    301
102    202    302
103    203    303
104    204    304

E_CODE
101
102
103
104
201
202
203
204
301
302
303
304

E_CODE  E_DECS
101       A
102       B
103       C
104       D
201       E
202       F
203       G
204       H
301       I
302       J
303       K
304       L

CODE1   DESC1   CODE2   DESC2  CODE3  DESC3
101      A       201     E      301    I
102      B       202     F      302    J
103      C       203     G      303    K
104      D       204     H      304    L

SQL> with
  2    emp as (
  3     select 101 code, 201 code1, 301 code2 from dual union all
  4     select 102,    202,    302 from dual union all
  5     select 103,    203,    303 from dual union all
  6     select 104,    204,    304 from dual 
  7    ),
  8    E_con_desc as (
  9      select 101 e_code,  'A' e_decs from dual union all
 10      select 102,       'B' e_decs from dual union all
 11      select 103,       'C' e_decs from dual union all
 12      select 104,       'D' e_decs from dual union all
 13      select 201,       'E' e_decs from dual union all
 14      select 202,       'F' e_decs from dual union all
 15      select 203,       'G' e_decs from dual union all
 16      select 204,       'H' e_decs from dual union all
 17      select 301,       'I' e_decs from dual union all
 18      select 302,       'J' e_decs from dual union all
 19      select 303,       'K' e_decs from dual union all
 20      select 304,       'L' e_decs from dual
 21    )
 22  select e.code code1, d1.e_decs desc1,
 23         e.code1 code2, d2.e_decs desc2,
 24         e.code2 code3, d3.e_decs desc3
 25  from emp e, E_con_desc d1, E_con_desc d2, E_con_desc d3
 26  where d1.e_code = e.code
 27    and d2.e_code = e.code1
 28    and d3.e_code = e.code2
 29  /
     CODE1 D      CODE2 D      CODE3 D
---------- - ---------- - ---------- -
       101 A        201 E        301 I
       102 B        202 F        302 J
       103 C        203 G        303 K
       104 D        204 H        304 L